Your mobo has a support of PCI express x16 2.0 whereas these cards require PCI Express 3.0 x16. Cards either may not be able to run or if they are made to run they would run at PCI express 2.0 default.
PCIe 3.0 is a advanced standard than the PCIe 2.0. In order to have PCIe 3.0 option you have to change mobo. Just buy this card and use it on your current mobo. No need to change mobo as of now.
huh? Your motherboard has PCI-e 2.0. Unless you are going to get a new motherboard just for PCI-e 3.0 (hint: don't) I don't see the relevance. Obviously 3.0 is faster than 2.0 but it really doesn't matter. The 7770 will run just fine on your motherboard.